Ferromagnetism in ultrathin surface-free La0.7Sr0.3MnO3 layers in electrostatically defined heterostructures

Electrostatically defined perovskite oxide heterostructures, in which carriers are confined by the modulation of the A-site ion charge, offer new possibilities of tuning the magnetic properties of manganite oxides. We investigate the preferential orientation of ferromagnetic and antiferromagnetic moments in ultrathin ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ layers embedded in antiferromagnetic $\mathrm{Sr}{\mathrm{MnO}}_{3}$ as they undergo a metal-to-insulator transition with decreasing thickness. Our results evince the role of orbital occupation, metallicity, and competition of different magnetic phases, in absence of spurious effects occurring in thin films as a result of symmetry breaking at ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ interfaces and of incorporation of oxygen vacancies.